/*
 * SPDX-FileCopyrightText: 2025 UnionTech Software Technology Co., Ltd.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

use crate::error::ZipError;

use std::fmt::{Debug, Formatter};
use std::hash::Hash;
use std::io::{self, Write};
use std::num::Wrapping;

/// A container to hold the current key state

#[derive(Clone, Copy, Hash, Ord, PartialOrd, Eq, PartialEq)]
pub(crate) struct ZipCryptoKeys {
    key_0: Wrapping<u32>,
    key_1: Wrapping<u32>,
    key_2: Wrapping<u32>,
}

impl Debug for ZipCryptoKeys {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        f.write_fmt(format_args!(
            "ZipCryptoKeys::of({:#10x},{:#10x},{:#10x})",
            self.key_0, self.key_1, self.key_2
        ))
    }
}

impl ZipCryptoKeys {
    const fn new() -> ZipCryptoKeys {
        ZipCryptoKeys {
            key_0: Wrapping(0x12345678),
            key_1: Wrapping(0x23456789),
            key_2: Wrapping(0x34567890),
        }
    }

    #[allow(unused)]
    pub const fn of(key_0: u32, key_1: u32, key_2: u32) -> ZipCryptoKeys {
        ZipCryptoKeys {
            key_0: Wrapping(key_0),
            key_1: Wrapping(key_1),
            key_2: Wrapping(key_2),
        }
    }

    fn update(&mut self, input: u8) {
        self.key_0 = ZipCryptoKeys::crc32(self.key_0, input);
        self.key_1 =
            (self.key_1 + (self.key_0 & Wrapping(0xff))) * Wrapping(0x08088405) + Wrapping(1);
        self.key_2 = ZipCryptoKeys::crc32(self.key_2, (self.key_1 >> 24).0 as u8);
    }

    fn stream_byte(&mut self) -> u8 {
        let temp: Wrapping<u16> = Wrapping(self.key_2.0 as u16) | Wrapping(3);
        ((temp * (temp ^ Wrapping(1))) >> 8).0 as u8
    }

    fn decrypt_byte(&mut self, cipher_byte: u8) -> u8 {
        let plain_byte: u8 = self.stream_byte() ^ cipher_byte;
        self.update(plain_byte);
        plain_byte
    }

    #[allow(dead_code)]
    fn encrypt_byte(&mut self, plain_byte: u8) -> u8 {
        let cipher_byte: u8 = self.stream_byte() ^ plain_byte;
        self.update(plain_byte);
        cipher_byte
    }

    fn crc32(crc: Wrapping<u32>, input: u8) -> Wrapping<u32> {
        (crc >> 8) ^ Wrapping(CRCTABLE[((crc & Wrapping(0xff)).0 as u8 ^ input) as usize])
    }
    pub(crate) fn derive(password: &[u8]) -> ZipCryptoKeys {
        let mut keys = ZipCryptoKeys::new();
        for byte in password.iter() {
            keys.update(*byte);
        }
        keys
    }
}

/// A ZipCrypto reader with unverified password
pub struct ZipCryptoReader<R> {
    file: R,
    keys: ZipCryptoKeys,
}

#[allow(dead_code)]
pub enum ZipCryptoValidator {
    PkzipCrc32(u32),
    InfoZipMsdosTime(u16),
}

impl<R: std::io::Read> ZipCryptoReader<R> {
    /// Note: The password is `&[u8]` and not `&str` because the
    /// [zip specification](https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.3.TXT)
    /// does not specify password encoding (see function `update_keys` in the specification).
    /// Therefore, if `&str` was used, the password would be UTF-8 and it
    /// would be impossible to decrypt files that were encrypted with a
    /// password byte sequence that is unrepresentable in UTF-8.
    #[allow(dead_code)]
    pub fn new(file: R, password: &[u8]) -> ZipCryptoReader<R> {
        ZipCryptoReader {
            file,
            keys: ZipCryptoKeys::derive(password),
        }
    }

    /// Read the ZipCrypto header bytes and validate the password.
    #[allow(dead_code)]
    pub fn validate(
        mut self,
        validator: ZipCryptoValidator,
    ) -> Result<ZipCryptoReaderValid<R>, ZipError> {
        // ZipCrypto prefixes a file with a 12 byte header
        let mut header_buf = [0u8; 12];
        self.file.read_exact(&mut header_buf)?;
        for byte in header_buf.iter_mut() {
            *byte = self.keys.decrypt_byte(*byte);
        }

        match validator {
            ZipCryptoValidator::PkzipCrc32(crc32_plaintext) => {
                // PKZIP before 2.0 used 2 byte CRC check.
                // PKZIP 2.0+ used 1 byte CRC check. It's more secure.
                // We also use 1 byte CRC.

                if (crc32_plaintext >> 24) as u8 != header_buf[11] {
                    return Err(ZipError::InvalidPassword);
                }
            }
            ZipCryptoValidator::InfoZipMsdosTime(last_mod_time) => {
                // Info-ZIP modification to ZipCrypto format:
                // If bit 3 of the general purpose bit flag is set
                // (indicates that the file uses a data-descriptor section),
                // it uses high byte of 16-bit File Time.
                // Info-ZIP code probably writes 2 bytes of File Time.
                // We check only 1 byte.

                if (last_mod_time >> 8) as u8 != header_buf[11] {
                    return Err(ZipError::InvalidPassword);
                }
            }
        }

        Ok(ZipCryptoReaderValid { reader: self })
    }
}
#[allow(unused)]
pub(crate) struct ZipCryptoWriter<W> {
    pub(crate) writer: W,
    pub(crate) buffer: Vec<u8>,
    pub(crate) keys: ZipCryptoKeys,
}
impl<W: std::io::Write> ZipCryptoWriter<W> {
    #[allow(unused)]
    pub(crate) fn finish(mut self, crc32: u32) -> std::io::Result<W> {
        self.buffer[11] = (crc32 >> 24) as u8;
        for byte in self.buffer.iter_mut() {
            *byte = self.keys.encrypt_byte(*byte);
        }
        self.writer.write_all(&self.buffer)?;
        self.writer.flush()?;
        Ok(self.writer)
    }
}
impl<W: std::io::Write> std::io::Write for ZipCryptoWriter<W> {
    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
        self.buffer.extend_from_slice(buf);
        Ok(buf.len())
    }
    fn flush(&mut self) -> std::io::Result<()> {
        Ok(())
    }
}

/// A ZipCrypto reader with verified password
pub struct ZipCryptoReaderValid<R> {
    reader: ZipCryptoReader<R>,
}

impl<R: std::io::Read> std::io::Read for ZipCryptoReaderValid<R> {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        // Note: There might be potential for optimization. Inspiration can be found at:
        // https://github.com/kornelski/7z/blob/master/CPP/7zip/Crypto/ZipCrypto.cpp

        let n = self.reader.file.read(buf)?;
        for byte in buf.iter_mut().take(n) {
            *byte = self.reader.keys.decrypt_byte(*byte);
        }
        Ok(n)
    }
}

impl<R: std::io::Read> ZipCryptoReaderValid<R> {
    /// Consumes this decoder, returning the underlying reader.
    #[allow(dead_code)]
    pub fn into_inner(self) -> R {
        self.reader.file
    }
}

static CRCTABLE: [u32; 256] = [
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
    0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
    0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
    0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
    0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
    0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
    0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
    0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
    0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
    0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
    0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
    0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
    0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
    0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
    0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
    0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
    0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
    0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
    0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
    0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
    0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
    0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
];

pub struct ZipCryptoEncryptor<W: Write> {
    inner: W,
    keys: ZipCryptoKeys,
    crc32: u32,
    header_written: bool,
}

impl<W: Write> ZipCryptoEncryptor<W> {
    pub fn new(inner: W, password: &str, crc32: u32) -> io::Result<Self> {
        let keys = ZipCryptoKeys::derive(password.as_bytes());
        Ok(Self {
            inner,
            keys,
            crc32,
            header_written: false,
        })
    }

    fn write_header(&mut self) -> io::Result<()> {
        if !self.header_written {
            let mut header = vec![0u8; 12];
            // 填充随机数据
            use rand::RngCore;
            rand::rng().fill_bytes(&mut header[..10]);

            // 设置CRC32验证字节
            header[11] = (self.crc32 >> 24) as u8;

            // 加密头部
            for byte in &mut header {
                *byte = self.keys.encrypt_byte(*byte);
            }

            self.inner.write_all(&header)?;
            self.header_written = true;
        }
        Ok(())
    }

    pub fn replace_writer(&mut self, new_writer: W) -> anyhow::Result<()> {
        // 先刷新当前的writer
        println!(
            "Replacing writer, current type: {}",
            std::any::type_name::<W>()
        );
        self.inner.flush()?;
        self.inner = new_writer;
        Ok(())
    }
}

impl<W: Write> Write for ZipCryptoEncryptor<W> {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        self.write_header()?;

        let mut encrypted = Vec::with_capacity(buf.len());
        for &byte in buf {
            encrypted.push(self.keys.encrypt_byte(byte));
        }

        self.inner.write_all(&encrypted)?;
        Ok(buf.len())
    }

    fn flush(&mut self) -> io::Result<()> {
        self.inner.flush()
    }
}

impl<W: Write> ZipCryptoEncryptor<W> {
    pub fn finish(mut self) -> io::Result<W> {
        self.flush()?;
        Ok(self.inner)
    }
}

/// 流式ZIP解密器
#[allow(dead_code)]
pub struct ZipCryptoDecryptor {
    keys: ZipCryptoKeys,
    header_read: bool,
    expected_crc: u32,
}

impl ZipCryptoDecryptor {
    /// 创建新的解密器
    #[allow(dead_code)]
    pub fn new(password: &str, expected_crc: u32) -> Self {
        Self {
            keys: ZipCryptoKeys::derive(password.as_bytes()),
            header_read: false,
            expected_crc,
        }
    }

    /// 解密一块数据
    /// 如果是首次调用,会先处理12字节加密头并验证密码
    #[allow(dead_code)]
    pub fn decrypt_chunk(&mut self, data: &[u8]) -> std::io::Result<Vec<u8>> {
        let mut result = Vec::new();

        if !self.header_read {
            // 首块数据必须至少包含12字节头
            if data.len() < 12 {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::InvalidData,
                    "First chunk too small for header",
                ));
            }

            // 解密并验证头部
            let mut header = [0u8; 12];
            for i in 0..12 {
                header[i] = self.keys.decrypt_byte(data[i]);
            }

            // 验证密码(使用CRC32的高字节)
            if (self.expected_crc >> 24) as u8 != header[11] {
                return Err(std::io::Error::new(
                    std::io::ErrorKind::InvalidData,
                    "Invalid password",
                ));
            }

            self.header_read = true;

            // 解密剩余数据
            for &byte in &data[12..] {
                result.push(self.keys.decrypt_byte(byte));
            }
        } else {
            // 非首块,直接解密所有数据
            for &byte in data {
                result.push(self.keys.decrypt_byte(byte));
            }
        }

        Ok(result)
    }
}

// 添加新的公开方法
#[allow(dead_code)]
pub fn encrypt_data(data: &[u8], password: &str, crc32: u32) -> std::io::Result<Vec<u8>> {
    let mut keys = ZipCryptoKeys::derive(password.as_bytes());
    let mut encrypted = Vec::with_capacity(data.len() + 12);

    // 生成12字节随机头
    let mut header = [0u8; 12];
    use rand::RngCore;
    rand::rng().fill_bytes(&mut header);

    header[11] = (crc32 >> 24) as u8;

    // 加密头
    for &byte in &header {
        encrypted.push(keys.encrypt_byte(byte));
    }

    // 加密数据
    for &b in data {
        encrypted.push(keys.encrypt_byte(b));
    }

    Ok(encrypted)
}

#[allow(dead_code)]
pub fn decrypt_data(
    data: &[u8],
    password: &str,
    expected_crc: Option<u32>,
) -> std::io::Result<Vec<u8>> {
    let mut keys = ZipCryptoKeys::derive(password.as_bytes());
    let mut decrypted = Vec::with_capacity(data.len());

    // 解密数据
    for &byte in data {
        decrypted.push(keys.decrypt_byte(byte));
    }

    // 如果有提供CRC校验值，则验证
    if let Some(crc) = expected_crc {
        if decrypted.len() >= 12 && (crc >> 24) as u8 != decrypted[11] {
            return Err(std::io::Error::new(
                std::io::ErrorKind::InvalidData,
                "Invalid password or corrupted data",
            ));
        }
    }

    Ok(decrypted)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_stream_encrypt() -> io::Result<()> {
        let password = "test123";
        let crc32 = 0xAABBCCDD;
        let data = b"Hello World!";

        // 创建加密器
        let mut output = Vec::new();
        let mut encryptor = ZipCryptoEncryptor::new(&mut output, password, crc32)?;

        // 分块写入数据
        encryptor.write_all(&data[..6])?; // "Hello "
        encryptor.write_all(&data[6..])?; // "World!"
        encryptor.finish()?;

        // 验证输出长度 (12字节头 + 12字节数据)
        assert_eq!(output.len(), 24);
        Ok(())
    }

    #[test]
    fn test_stream_encrypt_decrypt() -> io::Result<()> {
        let password = "test123";
        let crc32 = 0xAABBCCDD;
        let data = b"Hello World!";

        // 加密
        let mut encrypted = Vec::new();
        {
            let mut encryptor = ZipCryptoEncryptor::new(&mut encrypted, password, crc32)?;
            encryptor.write_all(data)?;
            encryptor.finish()?;
        }

        // 解密
        let mut decryptor = ZipCryptoDecryptor::new(password, crc32);
        let decrypted = decryptor.decrypt_chunk(&encrypted)?;

        // 验证解密结果
        assert_eq!(&decrypted[..], data); // 跳过12字节头
        Ok(())
    }

    #[test]
    fn test_wrong_password() {
        let password = "test123";
        let wrong_password = "wrong";
        let crc32 = 0xAABBCCDD;
        let data = b"Hello World!";

        // 加密
        let mut encrypted = Vec::new();
        {
            let mut encryptor = ZipCryptoEncryptor::new(&mut encrypted, password, crc32).unwrap();
            encryptor.write_all(data).unwrap();
            encryptor.finish().unwrap();
        }

        // 用错误密码解密
        let mut decryptor = ZipCryptoDecryptor::new(wrong_password, crc32);
        let result = decryptor.decrypt_chunk(&encrypted);

        // 应该返回错误
        assert!(result.is_err());
    }
}
